Power spectral analysis of cosmic ray intensity recorded by neutron monitors at Calgary and Deep River, Alberta, was carried out over a wide range of frequencies from 3¿10-9 Hz to 6¿10-6 Hz (periodicities from 2 days to 11 years) during the epoch 1965-1989 and revealed different behavior of the power spectral density for the three ranges of frequency domains. At low frequencies corresponding to the periodicity T≈20 months the power spectrum shows an abrupt change in the level and profile of power spectral density (PSD). This indicates that the processes responsible for the long-period variations are different from the one which causes short-period variations. At middle frequencies corresponding to periodicities between 6 and 18 months, the PSD indicates that the periodicities are not stable and show a transient character over the entire epoch of analysis. The PSD for periods T≈27 days indicates an 11 year recurring tendency related to solar activity. The PSD for periods T>27 days indicates a depression during the minimum of solar activity showing a 22 year recurring tendency and suggests that it is controlled by drift effects which are correlated to the solar polar field reversal. For higher frequencies f>2¿10-6 Hz corresponding to periods T<6 days, the slope of the PSD is found to be similar to that of the interplanetary magnetic field inhomogeneities measured at different radial distances between 1 and 30 AU. ¿American Geophysical Union 1991